Testing extended for-loop

result.txt

old : 10times : 1msec
old : 100times : 7msec
old : 1000times : 39msec
old : 10000times : 44msec
old : 100000times : 374msec
old : 500000times : 1814msec
extended : 10times : 0msec
extended : 100times : 3msec
extended : 1000times : 22msec
extended : 10000times : 52msec
extended : 100000times : 544msec
extended : 500000times : 2488msec
old : 10times : 1msec
old : 100times : 0msec
old : 1000times : 3msec
old : 10000times : 31msec
old : 100000times : 326msec
old : 500000times : 1810msec
extended : 10times : 0msec
extended : 100times : 0msec
extended : 1000times : 3msec
extended : 10000times : 33msec
extended : 100000times : 387msec
extended : 500000times : 2171msec
old : 10times : 0msec
old : 100times : 0msec
old : 1000times : 2msec
old : 10000times : 22msec
old : 100000times : 294msec
old : 500000times : 1747msec
extended : 10times : 1msec
extended : 100times : 0msec
extended : 1000times : 3msec
extended : 10000times : 32msec
extended : 100000times : 373msec
extended : 500000times : 2167msec
old : 10times : 0msec
old : 100times : 0msec
old : 1000times : 2msec
old : 10000times : 23msec
old : 100000times : 345msec
old : 500000times : 1733msec
extended : 10times : 0msec
extended : 100times : 1msec
extended : 1000times : 3msec
extended : 10000times : 38msec
extended : 100000times : 392msec
extended : 500000times : 2170msec
old : 10times : 0msec
old : 100times : 0msec
old : 1000times : 2msec
old : 10000times : 22msec
old : 100000times : 302msec
old : 500000times : 1794msec
extended : 10times : 0msec
extended : 100times : 0msec
extended : 1000times : 3msec
extended : 10000times : 32msec
extended : 100000times : 390msec
extended : 500000times : 2376msec

TestExtendedFor.java

import java.util.ArrayList;
import java.util.List;

/**
 * 拡張for文のテスト
 * 
 * @author tksmaru
 * 
 */
public class TestExtendedFor {

	public static void main(String[] args) {

		TestExtendedFor tester = new TestExtendedFor();

		// 最適化の恩恵を見てみるために５回繰り返してみる
		for (int i = 0; i < 5; i++) {

			tester.oldFor(tester.setUp(10));
			tester.oldFor(tester.setUp(100));
			tester.oldFor(tester.setUp(1000));
			tester.oldFor(tester.setUp(10000));
			tester.oldFor(tester.setUp(100000));
			tester.oldFor(tester.setUp(500000));

			tester.extendedFor(tester.setUp(10));
			tester.extendedFor(tester.setUp(100));
			tester.extendedFor(tester.setUp(1000));
			tester.extendedFor(tester.setUp(10000));
			tester.extendedFor(tester.setUp(100000));
			tester.extendedFor(tester.setUp(500000));
		}
	}

	/**
	 * 要素がloop数のListを生成します。
	 * 
	 * @param loop
	 * @return
	 */
	public List<String> setUp(int loop) {
		List<String> list = new ArrayList<String>();
		for (int i = 0; i < loop; i++) {
			list.add(String.valueOf(i));
		}
		return list;
	}

	/**
	 * 拡張for文でStringBufferの文字列連結を行う。
	 * 
	 * @param list
	 */
	public void extendedFor(List<String> list) {
		long start = System.currentTimeMillis();
		// 100回試行
		for (int i = 0; i < 100; i++) {
			StringBuffer buff = new StringBuffer();
			for (String name : list) {
				buff.append(name);
			}
		}
		long fin = System.currentTimeMillis();
		System.out.println("extended : " + list.size() + "times : "
				+ (fin - start) + "msec");
	}

	/**
	 * 既存のfor文でStringBufferの文字列連結を行う。
	 * 
	 * @param list
	 */
	public void oldFor(List<String> list) {
		long start = System.currentTimeMillis();
		// 100回試行
		for (int i = 0; i < 100; i++) {
			StringBuffer buff = new StringBuffer();
			for (int j = 0; j < list.size(); j++) {
				buff.append(list.get(j));
			}
		}
		long fin = System.currentTimeMillis();
		System.out.println("old : " + list.size() + "times : " + (fin - start)
				+ "msec");
	}
}